EP0483914A1 - Vorrichtung zur selektiven Auffindung eines Objekts - Google Patents

Vorrichtung zur selektiven Auffindung eines Objekts Download PDF

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Publication number
EP0483914A1
EP0483914A1 EP91202762A EP91202762A EP0483914A1 EP 0483914 A1 EP0483914 A1 EP 0483914A1 EP 91202762 A EP91202762 A EP 91202762A EP 91202762 A EP91202762 A EP 91202762A EP 0483914 A1 EP0483914 A1 EP 0483914A1
Authority
EP
European Patent Office
Prior art keywords
signal
elementary
displacement
called
output
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP91202762A
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English (en)
French (fr)
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EP0483914B1 (de
Inventor
Raoul Société Civile S.P.I.D. Florent
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Laboratoires dElectronique Philips SAS
Koninklijke Philips NV
Original Assignee
Laboratoires dElectronique Philips SAS
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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Publication date
Application filed by Laboratoires dElectronique Philips SAS, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Laboratoires dElectronique Philips SAS
Publication of EP0483914A1 publication Critical patent/EP0483914A1/de
Application granted granted Critical
Publication of EP0483914B1 publication Critical patent/EP0483914B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/20—Analysis of motion
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/78—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using electromagnetic waves other than radio waves
    • G01S3/782—Systems for determining direction or deviation from predetermined direction
    • G01S3/785—Systems for determining direction or deviation from predetermined direction using adjustment of orientation of directivity characteristics of a detector or detector system to give a desired condition of signal derived from that detector or detector system
    • G01S3/786—Systems for determining direction or deviation from predetermined direction using adjustment of orientation of directivity characteristics of a detector or detector system to give a desired condition of signal derived from that detector or detector system the desired condition being maintained automatically
    • G01S3/7864—T.V. type tracking systems

Definitions

  • the invention relates to a device for the selective detection of moving objects.
  • the invention finds its application in, for example, surveillance systems, or in devices for preventing collisions with moving objects such as cars.
  • the technical problem which arises for those skilled in the art in the implementation of motion tracking algorithms for example, is to have a device capable, from a set of spatial coordinates, of providing a measurement of confidence allowing to decide, if this set of coordinates can be seen as coming from an object moving in a coherent way, relative to a criterion that one gives oneself, or not, and if this object must be selected or not.
  • the object of the present invention is to provide a device capable of selecting objects on the basis of their movement efficiency.
  • this object is achieved by means of a device as defined in the preamble, this device comprising: first means with a first output for a so-called straight line displacement signal representative of the measured amount of displacement in straight line of the object during a said first time interval, second means with a second output for a so-called effective distance signal representative of the sum of the measured distances actually traveled by the object during time subintervals of this time interval, comparison means having inputs coupled to receive the straight line displacement signal and the effective distance signal, and a so-called selection output to provide a so-called selection signal which indicates a selection when the energy of the straight line displacement signal exceeds a predetermined fraction of the energy of the effective distance signal.
  • the first and second measurements can be based for example on the position data acquired from successive images in which the object appears, or else from observation of its speed for example by using the Doppler effect.
  • the first and second measurements can therefore use different acquisition sources for measuring the displacements and the distances respectively.
  • the advantage is that the measurement remains valid in the case where the mobile makes U-turns in a short time.
  • the comparison of the displacement in a straight line with the distance actually traveled can in principle be carried out by calculating the sum of the square of the distances and displacements along axes of separate coordinates and by comparing these quantities.
  • this device has the advantage of providing a measurement which responds well to the criterion of movement efficiency, when the mobile moves efficiently in at least one direction parallel to one of the coordinate axes.
  • this device will make it possible to decree that a mobile affected by a sinusoidal movement in one of the two directions, has an effective movement. It suffices for this that the period of the sinusoid is sufficiently large compared to the amplitude.
  • This device also follows motives well in U-turns, not only because it takes into account the components of the distances along the coordinate axes, but also because it allows the integration of the measurement over a lapse of time. given time. Indeed, if we considered only an elementary measurement, that is to say that which looks at the evolution of the moving body between two successive instants, this measurement would become false in the case of a U-turn. At on the contrary, by integrating the measurement over a period of time covering a sufficient number of successive elementary measurements, the effect of the U-turn is erased.
  • slow moving we mean moving whose displacement is of the order of a few pixels in time which separates two consecutive images.
  • the device for real-time measurement of the movement efficiency of a mobile moving on a trajectory T, in a sequence of images is based on the algorithm defined below
  • the movement efficiency is the ratio between the distance L1 measured in a straight line between two points P n and P m of the trajectory T, these points being identified at two given times separated by a time lapse ⁇ 1, and the distance L2 actually traveled by the mobile on this trajectory T during this period of time.
  • the elementary displacement P n P m on the trajectory T is broken down into its two components along two axes of planar spatial coordinates of the image, for example two axes of orthogonal coordinates and .
  • the components of P n -P m respectively are denoted below D x, k and D y, k where k is an index which may vary over time.
  • the movement efficiency measurement applied to a trajectory T includes a sum of displacements whose implementation poses problems.
  • the sequence of images to be studied can include, in addition to the mobile (s), quasi-static targets that one does not want to detect.
  • the aim is to provide a device providing a a measure of movement efficiency which does not depend on a scale factor.
  • the aim has been set to produce a device providing an average of the movement efficiency.
  • This problem is solved by weighting the measure of movement efficiency by the average number of significant displacements.
  • the average number of significant displacements is itself obtained by carrying out the weighted summation, according to the criterion defined above with respect to the summations of displacements, of the counting of significant displacements.
  • the measurement device first comprises a number N of branches equal to the number N of dimensions, of the space considered.
  • the measuring device has two branches 100 and 200 respectively.
  • the first branch 100 receives at the input node 1, the measurements of the coordinates D x, k along the axis
  • the second branch 200 receives at the input node 2
  • the measurements of the coordinates D x, k and D y, k are provided by an extractor known to those skilled in the art, an extractor which is not strictly speaking part of the invention.
  • a device with N branches would receive on these latter respectively the measurements of the coordinates along the N axes of space, denoted s (k).
  • the branch 10, or middle branch in FIG. 3, is coupled to the input 1 to receive the measurements D x, k along the axis , and includes a block 12 consisting of a first order recursive filter F ⁇ , defined by a forgetting factor ⁇ .
  • This filter receives the data stream D x, k invariant.
  • the coefficient ⁇ is linked to the time lapse ⁇ 1 over which we integrates the measurement, or the number of images n1 produced during the time ⁇ 1. This number of images n1 corresponds to the minimum error that can be obtained between the approximate value provided by the device and an exact average over n1 measurements.
  • the recursive filter F ⁇ takes its output h (k-1) and reinjects it at its input 1 by multiplying it by ⁇ . It follows that, by the calculation subsequent to order (k), its output h (k) is the sum of ⁇ .h (k-1) and of the input arriving at order k, which is D x, k .
  • ⁇ a forgetting factor applied to the filter F ⁇ .
  • forgetting factor is meant a factor ⁇ such that: 0 ⁇ ⁇ 1 (2)
  • the summation (3) is a weighted summation over an infinite period of time, because the terms of the summation tend towards zero when the exponent of the forget factor ⁇ tends to infinity.
  • the output h (k) of block 12 is denoted h x in FIG.
  • the branch 20, or lower branch in FIG. 3 is coupled to the input 1 to receive the measurements D x, k along the axis , and firstly comprises a block 21 constituted by an absolute value circuit AV
  • This circuit 21 can be constituted by a memory performing the affine function absolute value AV (for example a LUT, from the English Look-Up-TABLE).
  • the branch 20 then comprises, at the output of the circuit 21 of absolute value AV, a block 22 constituted by a filter F ⁇ identical to the recursive filter of the 1st order described previously with reference to the first branch 10, or middle branch of FIG. 3.
  • the output g x of block 22 of branch 20 therefore provides the sum of the absolute values of the distances D x, k traveled, which achieves the distance actually traveled L2 during the time lapse ⁇ 1, over a predetermined number of images n1.
  • the trajectory T with reference to FIG. 2 includes irregularities such that it returns to itself, the distance actually traveled by the mobile comprises the sum of the outward journey and the return journey.
  • the filter F ⁇ of the second branch 20 is identical to the filter of the first branch 10, that is to say assigned the same forgetting coefficient ⁇ , so as to obtain in one and the other branch, respectively the first 10 and the second 20, coherent approximations on the calculation of the distances respectively L1, distance in a straight line, and L2 distance actually traveled.
  • the branch 30, or lower branch with reference to FIG. 3, is coupled to the input 1 to receive the measurements D x, k along the axis and first comprises a block 31 performing a thresholding S of the input measurement D x, k .
  • This block 31 can be constituted by a memory circuit performing the thresholding function S (for example a LUT from the English LOOK-UP-TABLE).
  • this thresholding circuit S can cause, above a threshold fixed A PRIORI at 0.5 pixel, the displacement is then considered to be significant, and the thresholding circuit provides an output equal to a 1. Or, below the threshold, the displacement is then considered to be negligible, and the thresholding circuit provides an output equal to an O.
  • a block 32 constituted by a filter F ⁇ identical to those of the branches 10 and 20 previously described.
  • This block 32 performs a weighted summation of the significant displacements and provides the output f x which is the average number of significant displacements, during the period of time ⁇ 1, integrated over the number of images n1.
  • This operation is simply implemented by block 101, with reference to FIG. 3, which includes a multiplication circuit, a division circuit and an absolute value circuit.
  • This block 101 receives the functions f x , h x and g x and provides at output a measure of the average of the movement efficiency between two instants separated by the time lapse ⁇ 1 which corresponds to the forget factor ⁇ .
  • This F ⁇ filter is chosen with a structure similar to that of the F ⁇ filters already described. However, as another time scale is considered, the factor ⁇ is different from the factor ⁇ .
  • the measurements D y, k along the axis are also applied to the input 2 of the branch 200.
  • This branch comprises blocks identical to those of the branch 100, and identically connected.
  • This branch 200 provides at the output a measurement Py which is the average of the movement efficiency under the same conditions as p x .
  • N signals p In a space with M dimensions, we will have by analogy N signals p.
  • the outputs p x and p y of the branches 100 and 200 respectively are applied to a block 300 which performs the function "maximum of p x and P y " denoted M x, y .
  • This block 300 may consist of a conventional maximum circuit. In an N-dimensional space, the block 300 will perform the "maximum" function of all the signals p.
  • the output R of the maximum block 300 constitutes the measure of displacement efficiency sought.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Multimedia (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Theoretical Computer Science (AREA)
  • Image Analysis (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Optical Radar Systems And Details Thereof (AREA)
EP91202762A 1990-10-30 1991-10-24 Vorrichtung zur selektiven Auffindung eines sich bewegenden Objekts Expired - Lifetime EP0483914B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9013442 1990-10-30
FR9013442A FR2668591A1 (fr) 1990-10-30 1990-10-30 Dispositif de mesure d'efficacite de mouvement.

Publications (2)

Publication Number Publication Date
EP0483914A1 true EP0483914A1 (de) 1992-05-06
EP0483914B1 EP0483914B1 (de) 1997-08-13

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EP91202762A Expired - Lifetime EP0483914B1 (de) 1990-10-30 1991-10-24 Vorrichtung zur selektiven Auffindung eines sich bewegenden Objekts

Country Status (5)

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US (1) US5187689A (de)
EP (1) EP0483914B1 (de)
JP (1) JPH04265888A (de)
DE (1) DE69127253T2 (de)
FR (1) FR2668591A1 (de)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5781477A (en) * 1996-02-23 1998-07-14 Micron Quantum Devices, Inc. Flash memory system having fast erase operation
US6243299B1 (en) 1998-02-27 2001-06-05 Micron Technology, Inc. Flash memory system having fast erase operation
JP3515926B2 (ja) * 1999-06-23 2004-04-05 本田技研工業株式会社 車両の周辺監視装置
US7266042B1 (en) 2006-03-31 2007-09-04 The United States Of America As Represented By The Secretary Of The Navy Multi-stage maximum likelihood target estimator
CN105738870B (zh) * 2014-12-10 2018-03-30 上海机电工程研究所 一种多模滤波方法
CN104751490B (zh) * 2015-04-09 2018-04-17 阔地教育科技有限公司 一种基于在线课堂的目标锁定方法及装置
CN104881882A (zh) * 2015-04-17 2015-09-02 广西科技大学 一种运动目标跟踪与检测方法
RU2703611C1 (ru) * 2019-01-28 2019-10-21 Акционерное общество "Стелла-К" Способ получения стереоскопических снимков с синтезированной величиной стереобазы

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
COMPUTER VISION GRAPHICS AND IMAGE PROCESSING. vol. 49, no. 3, Mars 1990, NEW YORK US pages 283 - 296; A.M. BRUCKSTEIN: 'on minimal energy trajectories' *
PROCEEDINGS OF SPIE-THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING -APPLICATIONS OF ARTIFICIAL INTRLLIGENCE VI vol. 937, 6 Avril 1988, ORLANDO US pages 505 - 511; D. THOMAS ET AL.: 'Motion filtering fot target extraction and tracking in infrared images' *

Also Published As

Publication number Publication date
EP0483914B1 (de) 1997-08-13
DE69127253D1 (de) 1997-09-18
JPH04265888A (ja) 1992-09-22
FR2668591A1 (fr) 1992-04-30
DE69127253T2 (de) 1998-02-19
US5187689A (en) 1993-02-16

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